The invention is designed for use in a conventional hot lime-soda ash process with zeolite softeners utilized by many companies for softening water, i.e. reducing the total hardness of water, expressed generally in terms of calcium carbonate, which is the hardest salt of major concern, but including carbonates and other salts of water hardening materials such as magnesium, calcium and iron. The total hardness of the water is reduced by decreasing the parts per million (ppm) of calcium carbonate (CaCO.sub.3) in the water. In such systems, the water is finally treated in a zeolite softener by filtering it through a bed of sodium zeolite resin. Prior to this final treatment, it is necessary to pass the water through a coal filter having a bed of anthracite coal. Unfortunately, particles of coal are carried by the water from the filter into the softener where they eventually clog and destroy the chemical ion exchange of the water with the sodium zeolite resin. A fouled up resinous bed of sodium zeolite must be removed and replaced. To do this is very time consuming and costly. The invention is directed to solving this problem by removing any particles of coal from the water, prior to the circulation of the water to the zeolite softener.
Briefly stated, the invention is in a system of treating water to reduce the hardness of the water by successively filtering the water through a bed of coal and a resinous bed of sodium zeolite. A coal trap is interposed between these two beds for removing any particles of coal from the water, prior to the circulation of the water to the resinous bed of sodium zeolite. Consequently, the resinous bed of sodium zeolite will be kept clean and not become clogged and contaminated with coal which destroys the capacity and effectiveness of the resinous bed of sodium zeolite in reducing the total hardness of the water.